// Copyright (C) 2005 Igor Chesnokov, mailto:ichesnokov@gmail.com

// Copyright (C) 2005 Peder Holt

// Use, modification and distribution is subject to the Boost Software

// License, Version 1.0. (http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_TYPEOF_MSVC_TYPEOF_IMPL_HPP_INCLUDED

# define BOOST_TYPEOF_MSVC_TYPEOF_IMPL_HPP_INCLUDED

# include <boost/config.hpp>

# include <boost/detail/workaround.hpp>

# include <boost/mpl/int.hpp>

# include <boost/type_traits/is_function.hpp>

# include <boost/utility/enable_if.hpp>

namespace boost

{

    namespace type_of

    {

        //Compile time constant code

# if BOOST_WORKAROUND(BOOST_MSVC,>=1300) && defined(_MSC_EXTENSIONS)

        template<int N> struct the_counter;

        template<typename T,int N = 5/*for similarity*/>

        struct encode_counter

        {

            __if_exists(the_counter<N + 256>)

            {

                BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 257>::count));

            }

            __if_not_exists(the_counter<N + 256>)

            {

                __if_exists(the_counter<N + 64>)

                {

                    BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 65>::count));

                }

                __if_not_exists(the_counter<N + 64>)

                {

                    __if_exists(the_counter<N + 16>)

                    { 

                        BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 17>::count));

                    }

                    __if_not_exists(the_counter<N + 16>)

                    {

                        __if_exists(the_counter<N + 4>)

                        {

                            BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 5>::count));

                        }

                        __if_not_exists(the_counter<N + 4>)

                        {

                            __if_exists(the_counter<N>)

                            {

                                BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 1>::count));

                            }

                            __if_not_exists(the_counter<N>)

                            {

                                BOOST_STATIC_CONSTANT(unsigned,count=N);

                                typedef the_counter<N> type;

                            }

                        }

                    }

                }

            }

        };

# define BOOST_TYPEOF_INDEX(T) (encode_counter<T>::count)

# define BOOST_TYPEOF_NEXT_INDEX(next)

# else

        template<int N> struct encode_counter : encode_counter<N - 1> {};

        template<> struct encode_counter<0> {};

        //Need to default to a larger value than 4, as due to MSVC's ETI errors. (sizeof(int)==4)

        char (*encode_index(...))[5];

# define BOOST_TYPEOF_INDEX(T) (sizeof(*boost::type_of::encode_index((boost::type_of::encode_counter<1005>*)0)))

# define BOOST_TYPEOF_NEXT_INDEX(next) friend char (*encode_index(encode_counter<next>*))[next];

# endif

        //Typeof code

# if BOOST_WORKAROUND(BOOST_MSVC,==1300)

        template<typename ID>

        struct msvc_extract_type

        {

            template<bool>

            struct id2type_impl;

            typedef id2type_impl<true> id2type;

        };

        template<typename T, typename ID>

        struct msvc_register_type : msvc_extract_type<ID>

        {

            template<>

            struct id2type_impl<true>  //VC7.0 specific bugfeature

            {

                typedef T type;

            };

        };

# else 

        template<typename ID>

        struct msvc_extract_type

        {

            struct id2type;

        };

        template<typename T, typename ID>

        struct msvc_register_type : msvc_extract_type<ID>

        {

            typedef msvc_extract_type<ID> base_type;

            struct base_type::id2type // This uses nice VC6.5 and VC7.1 bugfeature

            {

                typedef T type;

            };

        };

# endif

        template<int ID>

        struct msvc_typeid_wrapper {

            typedef typename msvc_extract_type<mpl::int_<ID> >::id2type id2type;

            typedef typename id2type::type type;

        };

        //Workaround for ETI-bug for VC6 and VC7

        template<>

        struct msvc_typeid_wrapper<1> {

            typedef msvc_typeid_wrapper<1> type;

        };

        //Workaround for ETI-bug for VC7.1

        template<>

        struct msvc_typeid_wrapper<4> {

            typedef msvc_typeid_wrapper<4> type;

        };

        //Tie it all together

        template<typename T>

        struct encode_type

        {

            //Get the next available compile time constants index

            BOOST_STATIC_CONSTANT(unsigned,value=BOOST_TYPEOF_INDEX(T));

            //Instantiate the template

            typedef typename msvc_register_type<T,mpl::int_<value> >::id2type type;

            //Set the next compile time constants index

            BOOST_STATIC_CONSTANT(unsigned,next=value+1);

            //Increment the compile time constant (only needed when extensions are not active

            BOOST_TYPEOF_NEXT_INDEX(next);     

        };

        template<class T>

        struct sizer

        {

            typedef char(*type)[encode_type<T>::value];

        };

# ifdef BOOST_NO_SFINAE

        template<typename T>

            typename sizer<T>::type encode_start(T const&);

# else

        template<typename T> typename disable_if<

            typename is_function<T>::type, 

            typename sizer<T>::type>::type encode_start(T const&);

        template<typename T> typename enable_if<

            typename is_function<T>::type, 

            typename sizer<T>::type>::type encode_start(T&);

# endif

    }

}

# define BOOST_TYPEOF(expr) \

    boost::type_of::msvc_typeid_wrapper<sizeof(*boost::type_of::encode_start(expr))>::type

# define BOOST_TYPEOF_TPL(expr) typename BOOST_TYPEOF(expr)

# define BOOST_TYPEOF_NESTED_TYPEDEF_TPL(name,expr) \

    struct name {\

        template<typename T>\

        static boost::type_of::msvc_register_type<T,name> _typeof_register_function(const T&);\

        BOOST_STATIC_CONSTANT(int,_typeof_register_value=sizeof(_typeof_register_function(expr)));\

        typedef typename boost::type_of::msvc_extract_type<name>::id2type id2type;\

        typedef typename id2type::type type;\

    };

# define BOOST_TYPEOF_NESTED_TYPEDEF(name,expr) \

    struct name {\

        template<typename T>\

        static boost::type_of::msvc_register_type<T,name> _typeof_register_function(const T&);\

        BOOST_STATIC_CONSTANT(int,_typeof_register_value=sizeof(_typeof_register_function(expr)));\

        typedef boost::type_of::msvc_extract_type<name>::id2type id2type;\

        typedef id2type::type type;\

    };

#endif//BOOST_TYPEOF_MSVC_TYPEOF_IMPL_HPP_INCLUDED